Photonics represents a very promising technological platform for designing high-performance systems, with increasingly high bandwidth requirements.
By way of example, the novel multi-processor systems are capable of providing extremely high computing power requiring data transfer speeds greater than 100 Terabit/s. These data transfer speeds may be necessary for data exchanges between processing cores, particularly within a multi-core processor.
At the present time, optical interconnections are the only technology capable of transmitting such speeds. They can be achieved by the optical interconnections particularly using the Wavelength Division Multiplexing (WDM) technique. This technique makes it possible to propagate a plurality of optical signals of different wavelengths simultaneously in the same optical waveguide, without any risk of collision between the different signals. Wavelength multiplexing represents an economical solution for increasing the bandwidth capacity of the waveguide.
In more concrete terms, photonics is a promising technology for designing network-on-chip systems, since it makes it possible, besides the increase in the bandwidth, to do away with problems associated with the high density of electrical interconnections in this type of electronic systems by providing interconnections having a small size.
The use of optical interconnections instead of electrical interconnections in integrated circuits offers two further advantages. Firstly, the transmission of an optical signal via a waveguide makes it possible to shorten transmission times and thus reduce transmitted signal loss. Secondly, the loss of the optical signal propagated in the waveguide is independent of the data transfer speed, which may potentially generate energy savings and increases in the performances of the circuits designed in this way.
To be able to use optical interconnections in an integrated circuit, the use of a number of optical devices in the integrated circuit is required. This is the case of the following devices:                at least one optical source, particularly a laser source, suitable for generating and transmitting an optical signal intended to be propagated in the optical interconnections,        at least one optical modulator, for example implemented in the form of a microring resonator, for modulating the optical signal,        at least one optical bus, particularly a silicon waveguide, through which the modulated optical signal is transmitted,        at least one optoelectronic converter, particularly a photodiode, for detecting the optical signal and converting same into an electrical signal on reaching the destination thereof (i.e. on the arrival thereof at the input of a processing node).        